RE: Why is there gravity?
May 11, 2015 at 1:53 am
(This post was last modified: May 11, 2015 at 1:56 am by nihilistcat.)
(March 28, 2015 at 7:27 am)urlawyer Wrote: So gravity is awesome. It keeps my ass in my chair and my beer in the bottle (provided I hold it right side up). But why is it there? What causes it? Just things having mass? I've searched it up and all I got were ambiguous "We don't know"'s or "That's just how the universe works"'s.
Does anyone else know more on this subject? Is there even anyone studying this stuff?
We don't know exactly ... actually is the right answer. We do understand gravity extremely well, we know it can't be shielded against, it has infinite range, it's the weakest of the four fundamental forces, it causes time dilation, acceleration due to gravity (on earth) is ~9.8 m/s^2, recent experiments suggest that the speed of gravity is equal to the speed of light in a vacuum, etc. Newton approximated gravity (for most purposes) pretty well (gravity is proportional to mass), and Einstein gave the best description of gravity (a consequence of the curvature of spacetime), and Einsteins theory of relativity is one of the best tested scientific theories in history. But we don't know if gravity exists as a particle (quantum field theory postulates the "graviton" as a hypothetical particle which mediates gravitational force), but it's impossible to test this hypothesis at this point in time (practically speaking). There are experiments that are trying to detect gravitational waves, so hopefully we'll learn more in the near future; but for the time being, there's much we don't know about gravity.
This is a crude explanation (I'm a biologist, a physicist can obviously do a better job of explaining this, but hopefully this helps).